Currently, electronic industry and electrical industry are rapidly developing, and require electronic products to be developed in the direction of lightweight thinning, high performance, high reliability and environmental protection. Thus there is a higher demand on the printed circuit board and copper clad foil plate. The products thereof are required to have a high heat resistance, a low coefficient of thermal expansion, a high humidity resistance, environmental protection, flame retarding resistance, a low dielectric constant and dielectric loss and a high elastic modulus.
The combustion of copper clad plates of halides and antimonide not only produces a large volume of smoke and a unpleasant smell, but also emits hydrogen halide gas having a great toxicity and a strong causticity, which pollutes the environment and endangers human health. At present, a phosphorous-containing resin is generally and industrially used to achieve the flame retarding effect, i.e. epoxy resin corresponding to phosphorous-containing compounds DOPO or ODOPB. However, the impregnated sheet materials will cause many problems, such as low heat resistance, high water absorption, worse chemical resistance and the like.
In order to solve said problems, ZL200410051855.3 discloses improving phosphorous-containing epoxy resin by using the resin containing dihydrobenzoxazine to increase heat resistance, chemical resistance and to decrease water absorption. However, the resin containing dihydrobenzoxazine cannot achieve the fire performance standard V-0 in UL94. Moreover, such resin is very fragile and difficult to achieve the processing requirements on the printed circuit board. In addition, dihydrobenzoxazine per se has a very curing temperature of more than 200° C., so that it is difficult for the sheet materials to be completely cured.
CN1333014C discloses the technique of directly filling the macromolecular polyphenyl ether into said system, which is actually difficult to achieve the expected effect due to the difficulties of filling the organic macromolecular fillers, mixing and coating glue, and of homogeneous dispersion. The polymers cannot be plasticized unless the polyphenyl ether molecules are crosslinked to the polymers, which causes a slight reduction of the dielectric constant and dielectric loss. Polyphenyl ether per se has a flame retarding structure, but its flame resistance is greatly decreased due to the introduction of reactive groups and the reduction of molecular weight.